38o NINETEENTH CENTURY. FT. in. 



In this way he discovered that there was a regular de- 

 cisase in the number of spots for about five years and a 

 half, and then during the next five and a half years a gradual 

 increase, till they were very numerous indeed. This led him 

 lo think that the spots went through a complete round or 

 cycle of changes in about eleven years ; but as he found it 

 difficult to persuade other astronomers of the fact, he 

 actually carried on his daily observations for twenty years 

 longer, and then, at the end of thirty-four years of daily 

 observation, he was able to assert boldly that he had estab- 

 lished the truth of his theory. 



He had now kept an account of three periods of eleven 

 years. At the beginning of each of these periods the sun 

 was for some time smooth and almost free from spots : then 

 from year to year they increased, till, at the end of five and 

 a half years, as many as fifty or sixty could be seen at one 

 time. Then they decreased again till, at the end of another 

 five and a half years, the sun's face was comparatively smooth 

 and spotless. During the time that Schwabe was studying 

 these changes, other men in the different observatories of 

 Europe had noticed some remarkable peculiarities about the 

 magnetic needle. As long ago as 1 7 2 2, a famous astronomer 

 named Graham pointed out that the magnetic needle shifts 

 from side to side a little every day as the sun passes from 

 one side to the other of the globe. The movement is so 

 small that it cannot be seen without very accurate instru- 

 ments, but it shows that the sun's course does affect the 

 magnet ; and when very careful notes began to be made in 

 different observatories, it was noticed that this daily shifting 

 was greater some years than others. In 1 850 an astronomer 

 named Lament, of Munich, pointed out that the movement 

 became greater each year for about five and a half years, 

 and then grew less during the same period; this led Sh 



